Sensitive spectrofluorometry of cellular prion protein based on the on–off interaction between fluorescent dye-labelled aptamers and multi-walled carbon nanotubes†
Abstract
The very simple and general spectrofluorometry of cellular prion protein (PrPC) is reported in this contribution based on the on–off noncovalent interaction of fluorescent dye-labelled PrPC DNA aptamers with multi-walled carbon nanotubes (MWCNTs). Due to the π–π stacking interaction between the DNA bases of the aptamer and the carbon nanotubes, the fluorescent dye and the MWCNTs are brought into close proximity, which leads to fluorescence quenching with a ratio of up to 87%. However, further addition of PrPC, which disturbs the π–π interaction owing to the strong and specific binding of the aptamer to PrPC, driving the aptamer away from the surface of the MWCNTs, restored the quenched fluorescence. This recovered fluorescence intensity was found to be in linear proportion to the PrPC concentration in the range of 8.2 to 81.7 nM, which builds the basis of the spectrofluorometry of the cellular prion protein.